The present invention relates to glycidylester compositions, to a process for their preparation, to coating compositions and other curable compositions comprising the glycidylester compositions, and to cured products obtained by using the indicated curable compositions.
Coating compositions based on the reaction products of 2,2-bis-(4-hydroxyphenyl)propane and epichlorohydrin are known. The cured products prepared on the basis of these compositions are resistant against hydrolysis, however, they show a low ultraviolet resistance and are therefore not suitable for applications requiring a high degree of outdoor durability such as building parts or automotive topcoats.
Triglycidylesters which can be used in outdoor durable coatings and in moulding compositions are disclosed in European Patent Application No. 447360A (EP-A-447,360). The application discloses the product having high levels of hydrolyzable chlorine content. In example 2 of EP-A-447,360 which relates to the glycidation of the 2:1 adduct of hexahydrophthalic anhydride and dimethylolpropionic acid, the product obtained has a hydrolyzable chlorine content of 1.0% (10,000 mg/Kg). Such a high level of residual chlorine is generally undesirable in coating compositions.
European patent application No. 0518408A2, describes thermosetting resin compositions containing    (i) an advanced resin product obtainable by reacting            (a) a diglycidyl ester of an alpha,alpha′-dibranched dicarboxylic acid of the general formula I          with        (b) an alpha,alpha′-dibranched dicarboxylic acid of the general formula II         wherein n is 0 or 1,        wherein R is independently selected from the group consisting of straight and branched chain alkyl, cycloalkyl, arylalkyl and aryl, or both R's may form part of a substituted or unsubstituted cycloaliphatic ring system comprising 5, 6 or 8 carbon atoms, in which case n should be 0, wherein R1 is independently a hydrogen atom or a methyl group, wherein R2 is a single bond, substituted or unsubstituted alkylene or arylene or a radical of the formula III—(R3)m1—X—(R3)m2—  (III)         wherein m1 and m2 are independently 0 or 1,        wherein R3 is independently selected from the group consisting of substituted or unsubstituted alkylene, and X is a single bond or one of the following bridging groups 1 to V         wherein R4 is independently selected from the group consisting of C1 to C4 alkyl, with the proviso that when X is bridging group (V), m1 is 0 and when X is bridging group (VI), m2 is 0 and when n is 0, R2 is a single bond; and            (ii) a curing compound selected from the group consisting of amino resins blocked or unblocked (cyclo)aliphatic isocyanates, alpha,alpha′-dibranched cyclic anhydrides, acid-functional polyesters containing only alpha,alpha′-dibranched acid and ester groups, (cyclo)aliphatic amines, (cyclo)aliphatic polyamino amides, blocked or unblocked Lewis acids, and teritary amines.
The molar ratio of compounds (a) and (b) was preferably in the range of from 0.5 to 2.0.
Preferred reactants (a) are selected from diglycidyl ester of diethyl malonic acid, 2,2,5,5-tetramethyl adipic acid, sulphodipivalic acid and tetrapropyl adipic acid and preferred reactants (b) are selected from diethylmalonic acid, 2,2,5,5-tetramethyl adipic acid, sulphopivalic acid and tetrapropyl adipic acid.
It will be appreciated from the European patent application and other publications, referred to therein, that only very specifically structured diglycidyl esters of alpha,alpha′-dibranched dicarboxylic acid could be used as reactant in coating compositions that show a combination of acceptable hydrolytic stability, resistance of transesterification and acceptable weathering resistance.
International Application WO 96/11238 shows that epoxy resins containing cycloaliphatic nuclei have the disadvantage that they could only provide brittle coating films when cured. This brittleness made them unsuitable for coating applications, as brittleness often led to poor adhesion.
European patent application No. 0634434 A2 describes a process for the preparation of linear tertiary aliphatic carboxyl functional polyester resins, by reacting: (a) at least one compound A′ comprising one monofunctional primary- or secondary hydroxyl group and/or at least one compound A″ comprising one primary- or secondary hydroxyl group and one tertiary aliphatic carboxyl group; (b) at least one aromatic or cycloaliphatic dicarboxylic acid compound B comprising two aromatic- or secondary aliphatic carboxyl groups or the anhydride thereof; (c) at least one diol compound C comprising two aliphatic hydroxyl groups, which may independently be a primary or a secondary hydroxyl group; and (d) at least one dihydroxymonocarboxylic acid compound D comprising a tertiary aliphatic carboxyl group and two aliphatic hydroxyl groups, which may each independently be primary or secondary hydroxyl, the molar ratio of compounds A′:A″:B:C:D being M:N:X+Y+1:X:Y wherein M+N=2, X ranges from 2 to 8 and Y ranges from 2−N to 8, at a temperature of from 100 to 240° C., until essentially all the non-tertiary carboxyl groups as initially present in the reaction mixture have been reacted. The linear tertiary aliphatic carboxyl functional polyesters were reacted with an excess epihalohydrin in the presence of a suitable base and optional catalyst to produce polyglycidylester resins.
The European patent application No. 0720997A2 describes certain linear tertiary carboxyl functional polyesters and epoxy functional polyester resins. These polyester resins were obtained by reaction of: a) at least one aromatic and/or cycloaliphatic carboxylic acid compound A comprising two aromatic- and/or secondary aliphatic carboxyl groups or the anhydride thereof, b) at least one hydroxyl compound B comprising two aliphatic hydroxyl groups, which groups each independently may be primary or secondary hydroxyl groups, c) at least one hydroxyl substituted carboxylic acid compound C comprising at least one tertiary aliphatic carboxyl group and two aliphatic hydroxyl groups, which groups each independently may be primary or secondary hydroxyl groups, and d) optionally one carboxylic acid compound D comprising one carboxyl group, the molar ratio of compounds A:B:C:D being (X+Y−1):X:Y:Z, wherein X ranges from 2 to 8, Y ranges from 2 to 8, and Z ranges from 0 to 2.
The International Patent Application WO 98/23661 describes linear, tertiary carboxyl functional polyester resins obtainable by reaction of a) at least one compound A1, comprising the reaction product of (i) a glycidylester of a mixture of synthetic highly branched saturated monocarboxylic acids isomers of formula (R1)(R2)(R3)—C—COOH wherein R1, R2 and R3 are alkyl groups of from 1 to 15 carbon atoms, of which at least one is methyl, each acid containing from 5 to 19 and preferably from 5 to 13 carbon atoms, and (ii) a mixture of said synthetic highly branched saturated monocarboxylic acids, in a molar ratio of 1:1; said component A1 being optionally mixed with hydroxy pivalic acid (A2) and/or hydrogenated diphenylolpropane (A3); b) at least one aromatic or cycloaliphatic dicarboxylic acid compound B, comprising two aromatic- or secondary aliphatic carboxyl groups or the anhydride thereof; optionally c) a dihydroxymono-carboxylic acid compound C comprising a tertiary aliphatic carboxyl group and two aliphatic hydroxyl groups, which may each independently be primary or secondary hydroxyl; and optionally (d) a diol compound D comprising two aliphatic hydroxyl groups which may each independently be a primary or a secondary hydroxyl group; the molar ratio of compounds A1:A2+A3:B:C:D being A1:(2−A1):X+Y+1:X:Y, wherein A1 ranges from 0.1 to 2, wherein Y ranges from 0 to 6 and X ranges from 2 to 8, at a temperature of from 100 to 225° C., until essentially all the non-tertiary carboxyl groups as initially present in the reaction mixture have been reacted; polyglydicylesters derived from said polyester resins and coating compositions containing the polyester resin and/or the polyglycidyl resin.
The International Patent Application WO 98/24828 describes linear, tertiary carboxyl functional polyester resins obtained by reaction of (a) at least one 1,4-dicarboxylcyclohexane (A) optionally mixed with a minor weight fraction of an alkane dicarboxylic acid, containing in the range of from 8 to 16 carbon atoms (A′), (b) at least one dihydroxymonocarboxylic acid compound (B), comprising a tertiary aliphatic carboxyl group and two aliphatic hydroxyl groups, optionally (c) one diol compound (C) comprising two aliphatic hydroxyl groups, which may each independently be a primary or a secondary hydroxyl group, and optionally (d) a compound (D′) comprising one monofunctional primary or secondary hydroxyl group and/or a compound (D″) comprising one primary or secondary hydroxyl group and one tertiary aliphatic carboxyl group, the molar ratio of the compounds (A+A′):B:C:D′:D″ being X+Y+1:Y:X:M:N wherein M+N is the range of from 0 to 2, wherein X ranges from 2 to 8, and Y ranges from [2−(M+N)] to 8, at a temperature of from 100 to 225° C., until essentially all the non-tertiary carboxyl groups as initially present in the reaction mixture have been reacted; polyglycidylesters derived from said polyester resins; and coating compositions containing the polyester resin and/or the polyglycidylester resin.
International Application WO 98/42768 describes carboxyl functional polyester resins, epoxy functional polyester resins, derived from them, and coating compositions comprising these polyester compounds. The carboxyl functional polyester resins are obtained by reaction of: a) at least a compound of the formula: wherein x≧1, R1 and R2 each may represent an alkyl group having from 1 to 4 carbon atoms or wherein R1 and R2 may form together with the group —CH—(CH2)x—CH— a cycloalkyl group and preferably 1,4-cyclohexane dicarboxylic acid (A1), optionally mixed with minor amounts of a corresponding compound of formula I, wherein x=0 or anhydride thereof (A2), b) at least one diol compound B comprising two aliphatic hydroxyl groups which may each independently be a primary or a secondary hydroxyl group; optionally c) a dihydroxymonocarboxylic acid compound C, comprising a tertiary aliphatic carboxyl group and two aliphatic hydroxyl groups, which may each independently be primary or secondary hydroxyl; and optionally d) a trihydroxyalkane (D1) or tetrahydroxyalkane (D2), the molar ratio of compounds (A1+A2):B:C:D1:D2 being X+Y+2Z+3Q+P:X:Y:Z:Q, wherein X ranges from 1 to 8, Y ranges from 0 to 8, Z ranges from 0 to 4 and Q ranges from 0 to 3 and wherein p ranges from 1 to 5, and preferably 1-3 and is most preferably equal to 1, at a temperature of from 100 to 240° C., and preferably from 180 to 210° C. if any compound C is present, until essentially all the hydroxyl groups as initially present in the reaction mixture have been reacted.
Although the linear tertiary aliphatic carboxyl functional polyester resins and the polyglycidylesters provided a certain progress towards the requirements of outdoor durability (UV stability) and resistance against hydrolysis in the cured state, with reference to their use in modern economically applied coatings, there is still a need for further improvement of properties and/or decreased manufacturing costs.
It can be appreciated from the teachings of hereinbefore discussed EP 0634434A2, EP 0720997A2, WO 98/23661, WO 98/24828, WO 98/42768, that (i) in order to obtain improved cured coating properties, derived from a carboxyl functional polyester resin and an epoxy functional polyester resin, it could only be reached by either introducing terminal tertiary carboxyl groups in the polyester core block which are originating from a dicarboxylic acid reactant, wherein the carboxyl groups were removed from each other at least three methylene carbon atoms, or the original terminal carboxyl group in the initially prepared carboxyl functional polyester resin had to be reacted with a hydroxy branched alkane carboxylic acid, and that (ii) the presence of terminal carboxyl groups in the starting carboxyl functional polyester resin originating from a dicarboxylic acid or anhydride reactant, wherein the carboxyl groups are removed only two methylene carbon atoms such as phthalic acid or anhydride or 1,2-cyclohexanedicarboxylic acid or the anhydride thereof, should be avoided, as they could not be efficiently glycidated into the corresponding polyglycidyl polyesters.